Damn right everyone affected should be able to get a full refund.
Miss sold product. Deliberate deceit. May as well have been selling electric cars to people with no electric motors and petrol engines. Time since purchase irrelevant because it impossible for a normal owner to find out they'd been deceived.
And for all those saying how happy they are that their cars do pollute more and you won't let VW change them fine, your selfish we get that but that's your call, but still get the refund and then use it to buy a new one.